Phantom Basis sets simulation

Hello,
Currently I’m working on a phantom project that mimics mouse and human brain metabolites. For metabolite quantification, I have been utilizing the 7T brain basis sets available on the LCModel website to estimate metabolite concentrations in my phantom data. However, I have encountered inconsistencies in the fitting results across various ppm ranges, which suggests that the current basis sets may not be fully optimized for my specific phantom composition.

It would be greatly appreciated if you anyone could share any basis sets suitable for phantom metabolite estimation, as this would be highly beneficial prior to proceeding with the simulation of our own custom basis sets.

We have acquired spectra for individual metabolites as well as a combined phantom spectrum at TE = 18 ms using a 7T scanner, though we are capable of acquiring data at different echo times if necessary.

Any advice, guidance, or available scripts/code you could share for simulating phantom spectroscopy would be extremely valuable and much appreciated.

Appreciate your help.
Ishan

Hi @Ishan ,

The issue you are facing probably isn’t to do with suitability of the basis set for a phantom, but rather suitability for the specific sequence (and sequence parameters) you are using. Could you tell us the exact scanner, sequence, and sequence parameters (primarily echo time)?

Hi,
Its a Bruker MRI. We used PRESS sequence with echo time of 18ms.
Appreciate your help.
Thanks

Tagging @JamieNear and @cudalbu who should have more profound insight into the pulses and sequence timings on Bruker systems than I do.

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Hi Ishan,

Thanks for the details. You will need just a few more details to make a decent basis set for your data. Namely:

-TE1 and TE2 (the total echo time is divided into TE1 and TE2 such that TE1+TE2 = TE).
-Refocusing RF pulse waveform used.
-Refocusing RF pulse duration.

Once you have this information, you can use an MRS simulation tool to generate basis spectra for each metabolite. One tool that can do it is the ‘run_simPressShaped_fast.m’ tool in FID-A (FID-A/exampleRunScripts/run_simPressShaped_fast.m at master · CIC-methods/FID-A · GitHub). Another is the simulator in FSL-MRS (for more information see here: Basis Spectra Simulation — FSL-MRS 2.4.9 documentation).

Hope this gets you pointed in the right direction, but let me know if you have questions.

-Jamie

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